Formation degradation, such as asphalt milling, mining, or excavating, may result in wear on attack tools. Consequently, many efforts have been made to efficiently remove and replace these tools.
U.S. Pat. No. 6,585,326 to Sollami, which is herein incorporated by reference discloses a bit holder with its mating bit block utilizing a slight taper in the bit block bore, and a tapered shank on the bit holder that includes a second larger diameter tapered distal segment that combines with an axially oriented slot through the side wall of the bit holder shank to allow a substantially larger interference fit between the distal tapered shank segment and the bit block bore than previously known. When inserting the bit holder in the bit block bore, the distal first tapered segment resiliently collapses to allow insertion of that segment into the bit block bore. A second shank tapered portion is axially inwardly of the first distal tapered portion. The dual tapered shank allows the insertion of the bit holder in the bit block with an interference fit that provides a secure mounting of the bit holder in the bit block.
U.S. Pat. No. 3,865,437 to Crosby, which is herein incorporated by reference discloses a mining tool of the type in which a pick style bit is rotatably mounted in a bore in a support member and is retained therein by retaining means integrally formed on the bit. The retaining means advantageously takes the form of at least one radial projection on the rear end of the bit shank with the bit shank being slotted to impart radial resilience thereto so the bit can be assembled with the support member and readily disassembled therefrom while being retained therein during work operations. The support member may comprise a support block adapted for being fixed to a driver with a sleeve rotatable in a bore in the block and, in turn, rotatably receiving the bit. The sleeve may be slotted axially from the rear end so as to have lateral resilience; and the sleeve may be formed with one or more radial projections or protrusions at the rear end so that the sleeve, also, is releasably retained in the block by retaining means integral therewith.